Electrical impulses are sometimes applied to a patient's heart to terminate irregularities in the heart's operation. For example, defibrillation involves the discharge of an electrical impulse to a patient's heart to terminate a potentially fatal form of arrhythmia known as ventricular fibrillation. Less severe forms of arrhythmia can often be electrically terminated by a process referred to as synchronized cardioversion. For the purpose of the ensuing discussion, however, such processes involving the application of electrical energy to a patient will be collectively referred to as defibrillation.
The source of the electrical impulses used to terminate arrhythmic operation of the heart is a device known as a defibrillator. The defibrillator is electrically connected to the patient by a pair of cables and electrode assemblies. Typically, each assembly includes a handle, an electrode that provides the requisite electrical contact with the patient, and a discharge button for controlling the discharge of energy through the electrode to the patient.
The electrode assemblies are usually designed for either external or internal use. As will be appreciated, external electrode assemblies are employed noninvasively, with the electrodes positioned on the patient's chest. In contrast, internal electrode assemblies are employed during surgery and include electrodes that are applied directly to the patient's heart.
A conventional internal electrode assembly includes a handle and a permanently attached electrode. The handle, which is held like the handle of a pan, includes a discharge switch adjacent the end the electrode is attached to. This "pan handle" configuration, unfortunately, makes the assembly somewhat awkward to use in an opened chest cavity.
Because internal electrode assemblies are placed in contact with the heart, the internal assemblies must be sterile. Internal assemblies have traditionally been intended for reuse and must be sterilized after each use.
In that regard, although the assembly could be relatively quickly sterilized with steam, the handle of a conventional electrode assembly does not protect electrical components, such as the discharge switch, sufficiently to allow the handle to be steam sterilized. Thus, time-consuming ethylene oxide (ETO) sterilization processes are used for the entire assembly. If only a single pair of electrode assemblies are purchased for a defibrillator, the defibrillator cannot be used to perform internal defibrillation during those periods in which the assemblies are being sterilized. While this problem can be overcome by purchasing a supply of reusable assemblies for each defibrillator, system expense may increase significantly.
Alternatively, disposable electrode assemblies have been developed that are less expensive than conventional reusable assemblies. Still, a disposable assembly generally includes an electrode, handle, discharge button, cable, and connector. As a result, a single-use disposable electrode assembly is not particularly economical to use either.
As will be appreciated from the preceding remarks, it would be desirable to provide an internal electrode assembly that can be quickly sterilized. It would also be desirable to provide an internal electrode assembly that is simple and reliable in construction, as well as convenient to hold and use.